This proposal is concerned with the interplay between human interactions and the development of cognition and social-cognition during early phases of the life cycle. The project employs a range of age groupings of children and brings to bear a diversity of strategy, theory, and methodology. Each of four closely related projects shares a common perspective provided by a transactional framework. Together, these projects promise to advance beyond what is now known about interaction in development by extending the age ranges previously investigated, by emphasizing the causal role played by interactions, and by addressing basic psychological questions in terms of more highly specified characterizations of both human interaction and cognitive and social-cognitive development. The six investigators who constitute this Program Project Proposal represent diverse backgrounds in the study of development -- perception and cognition, language and communication, and social and personality psychology. Marc Bornstein proposes to study the origins of cognitive competences in the context of mother-infant dyadic interactions and of early infant information-processing capacities. Martin Braine proposes to study what linguistic information the young child needs from parental speech to acquire language and what features of the social environment promote language acquisition. Jerome Bruner and Henri Zukier propose to study two modes of communication in children, the narrative and the paradigmatic, and to assess the conditions under which one or the other obtains in interaction. Diane Ruble and E. Tory Higgins propose to study the relation between social interaction and the growth of children's understanding of social constructs. Taken together, therefore, the four projects address the significance and functions of interactions as antecedents, as mediating processes, and as consequences of the development of cognition and social cognition.